The anergy to tuberculin skin testing, sometimes noted in patients with tuberculous pleurisy, usually has been attributed to preferential sequestration of antigen reactive lymphocytes in the pleural space (1). However, this hypothesis has not been tested. Pleural effusions, in fact, contain an increased proportion of total (2) and immunoglobulin-G Fc receptor-positive (3) thymus-derived lymphocytes relative to peripheral blood, but the significance of these findings is uncertain.
We compared the function of peripheral blood and pleural fluid lymphocytes in three patients with culturally documented tuberculous pleurisy. Pleural fluid leukocyte counts ranged from 700 to 7200/µl with 95% to 99% mononuclear cells.